dojox/calendar/CalendarBase constructor handles properties oddly

Description

The constructor function for dojox/calendar/CalendarBase reads some values from args (for example, look in dojox/calendar/CalendarBase.js.uncompressed.js around line 295 and following, and see that we're reading DatePackage? from args. But what if we wanted to sublcass Calendar, and the subclass declaration provided a value for DatePackage? -- it wouldn't be picked up here.